BACKGROUND: Health workers, the core of health service delivery and a key driver of progress towards universal health coverage, must be available in sufficient numbers and distributed fairly to serve the entire population. In addition, the planning and management of the health workforce must be responsive to the changing needs of society, including changes in age structure and epidemiology. Considering these issues, this paper examines in historical perspective the evolution of postgraduate medical training and practice in Japan, from the late nineteenth century to the present. MAIN TEXT: When the first medical schools were established in the country towards the end of the nineteenth century, Japan was a largely agrarian society, with a population of about 30 million and an average life expectancy of 30-40 years. During the twentieth century, life expectancy and the national population continued to increase in a context of rapid economic growth. Since the 1980s, another demographic transition has occurred: low fertility rates and an aging society. As a result, the inputs and skills required from health professionals have changed considerably over time, posing new challenges to the national health sector and the management of human resources for health. CONCLUSIONS: The case of Japan offers valuable lessons for other countries experiencing a rapid epidemiological and demographic transition. To provide medical care that meets health priorities in the communities, we must consider not only the training of specialists, but also ensure the availability of a large cadre of physicians who possess basic skills and can provide patient-centred care. Furthermore, the Japanese experience shows that a highly hierarchical system and organisational culture are ill-suited to respond quickly to the changing demands of society.